Generating Signed APK

Android requires that all apps be digitally signed with a certificate before they can be installed, so to distribute your Android application via Google Play store, you'll need to generate a signed release APK. The Signing Your Applications page on Android Developers documentation describes the topic in detail. This guide covers the process in brief, as well as lists the steps required to package the JavaScript bundle.

Generating a signing key

You can generate a private signing key using keytool. On Windows keytool must be run from C:\Program Files\Java\jdkx.x.x_x\bin.

These are going to be global gradle variables, which we can later use in our gradle config to sign our app.

Note about saving the keystore:

Once you publish the app on the Play Store, you will need to republish your app under a different package name (losing all downloads and ratings) if you want to change the signing key at any point. So backup your keystore and don't forget the passwords.

Generating the release APK

Simply run the following in a terminal:

$ cd android
$ ./gradlew assembleRelease

Gradle's assembleRelease will bundle all the JavaScript needed to run your app into the APK. If you need to change the way the JavaScript bundle and/or drawable resources are bundled (e.g. if you changed the default file/folder names or the general structure of the project), have a look at android/app/build.gradle to see how you can update it to reflect these changes.

Note: Make sure gradle.properties does not include org.gradle.configureondemand=true as that will make the release build skip bundling JS and assets into the APK.

The generated APK can be found under android/app/build/outputs/apk/release/app-release.apk, and is ready to be distributed.

Testing the release build of your app

Before uploading the release build to the Play Store, make sure you test it thoroughly. First uninstall any previous version of the app you already have installed. Install it on the device using:

$ react-native run-android --variant=release

Note that --variant=release is only available if you've set up signing as described above.

You can kill any running packager instances, since all your framework and JavaScript code is bundled in the APK's assets.

Split APKs by ABI to reduce file size

By default, the generated APK has the native code for both x86 and ARMv7a CPU architectures. This makes it easier to share APKs that run on almost all Android devices. However, this has the downside that there will be some unused native code on any device, leading to unnecessarily bigger APKs.

You can create an APK for each CPU by changing the following line in android/app/build.gradle:

Upload both these files to markets which support device targetting, such as Google Play and Amazon AppStore, and the users will automatically get the appropriate APK. If you want to upload to other markets, such as APKFiles, which do not support multiple APKs for a single app, change the following line as well to create the default universal APK with binaries for both CPUs.